Agitator grate for underfeed stokers



March 30 1926.

' O. ARAM AGITATOR GRA'IE FOR UNDERFEED STOKERS Filed June 4, 1923 2 Sheets-Sheet 0110/4111": INVENTOR,

WITN ESSES:

ATTO R N EY March 30 1926. I

O. ARAM AGITATOR GRATE For: UNDERFEED STOKERS Filed June 4, 1923 2 Sheets-Sheet 01/0 flram INVENTOR E 5 S E N H W ATTORNEY Patented Mar. 30, 1926. I

UNITED STATES PATENT OFFICE.

OTTO ARAM, OF IHIEILADlliLIIPKIA, PENNSYLVANIA, ASSIGNOR TO WESTI NGHOITSE ELECTRIC AND MANUFACTURING CODANY, A. OOBIOBATION OF PENNSYLVANIA.

AGITATOB GBLTE FOB UNDEBFEED STONERS.

Application fled June 4,

My invention relates to stoker furnaces,-

more particularly to stoker furnaces having an underfeed grate followed by an overfeed grate, and it has for an object to provide in an apparatus of the character designated an overfeed grate construction which shall maintain the partially consumed fuel passing thereover in a relatively, fine and loose condition. A further object is to provide in conjunction with an underfeed grate an overfeed grate having a plurality of oscil lating grate sections so constructed and arranged that a vigorous agitation of the fuel thereon is obtained and the sifting of fuel and ash between the grates andbetween the sections of the overfeed grate is practically inhibited. A still further object of my invention is to provide in an overfeed grate having a plurality of oscillating grate sections a simple and efficient arrangement for oscillating the several grate sections.

These and other objects of my invention, which are made more manifest in the following description, may be attained by means of the apparatus illustrated in the ac' companying drawing, in which Fig. l is a view in longitudinal section through a stoker embodying my invention; and Fig. 2 is a plan view of the Stoker illustrated in Fig.

It has heretofore been proposed to utilize in stoker furnaces an overfeed grate receiving the residuum of fuel from the underfeed gram for the purpose of more completely burning out the combustible content of the residuum discharged from the underfeed grate. In the installations commonly employed, the residuum frequently agglomerates in large masses, particularly where fuels of low fusibility' are employed, which masses occlude the combustible portion of the residuum and prevent the burning thereof. I have found that if the refuse discharge from the underfeed grate is given a more vigorous and prolonged agitation in passing over the underfeed grate than is now customary, the

residuum of the fuel will have a lesser tend- 1923. Serial I'm 643,368.

ency to agglomerate in large masses and such clinker masses as do form will be broken up by the vigorous agitation, per mittm a. freer access of air to the com-' bustib e content of the residuum, and hence 1 ate sections providing a down,

more than usual length in the direction of travel of the fuel;

Referring to the drawing for a; more, detailed description of my invention, I show at 10 an underfeed grate delivering partially consumed fuelto an overfeed grate 11, from whence the refuse passes to a dump grateI 12 for-discharge to an ash pit 13.

Asshown, the underfeed grate 10 is composed of alternating retorts 15 and tuyere banks 16.' *The retorts are defined at the sides by wall members 17 supported upon end castings 18. and 19, which in turn are carried by. I-beams 20 and '21, respectively,

and at the bottom by deflecting plates 23, bottom plates 24and retort tuyeres 25. The tuyere banks 16 consist of a plurality of tuyere blocks 28 carried by the retort wall members 17 and superimposed one upon another in stepped relation. A ram box 30 is provided for .each retort, in which a re ciprocating ram 31 is disposed in theusual manner. A hopper 32 is arranged to supply fuel to the several ram boxes 30, as is the.

common practice in the construction of apparatus of this character. I F

The above arrangement is conventional and forms per se no part of the present invention, it being understood that various forms of underfeedgrate may be employed in carrying out the present invention in lieu of that above described and illustrated in.

the drawings.

The overfeed grate l l includes forward oscillating grate sections 40 and rear oscillating grate sections 41. The grate sections 4O a'redisposed contiguous to the retort end member 19. of'the u'nderfeedgrate- 10, and are pivotally mounted at their forward ends for oscillation upon a shaft 42. The shaft] 42 may be journalled in the side walls of the furnace in bearings'43. As shown, the grate sections 40 are hollow and provided with inlet, ports 44 which cooperate'with ports 45 in the member 19 to deliver an to the interior of the rate sections 40. Ports 46 in the upper sur ace of the grate sections 40 are provided for the delivery of air to the fuel bed thereon.

The rear oscillating grate sections 41 are centrally supported upon a shaft 50 journalled in the side Walls of the furnace in bearing 51. The grate sections 41 have 'po'rtions 53 extending forwardly from the shaft 51 upon which the rear end portions of the grate sections 40 are supported. Rearwardly extending portions 54 of the ate sections 41 terminate in arcuate spending flanges 55. Each of the grate sections 41 is also provided with ports 56 for the delivery of air to the fuel resting thereon.

The grate sections 41 may be'oscillated by any suitable mechanism. As shown, a reciprocating engine 60 of conventional construction acts through a connecting rod 61 and a crank arm 62 secured to the shaft 50 for effecting the desired oscillatory movement of the grate sections 41.

Air is supplied to an air chamber 70 of the underfeed grate 10 through a duct 71 and is distributed to the tuyeres 28 in the usual manner. A branch duct 72, controlled by a damper 73, leads from the chamber 70 to an auxiliary air chamber 74 disposed beneath the overfeed grate 11. Air from the chamber 74 passes through the ports 56 of the grate sections 41 tothe fuel bed thereon. 'As shown in the drawing, air for the grate sections 40 is taken from the chamber 70 through the cooperating ports 44 and 45. It is to be understood, however, that the grate sections 40 may be open to the chamber 74 and receive air therefrom instead of from the chamber 70. In'order to prevent an undue leakage of air at the rear edge of the grate sections 41, the rear wall of the chains ber 74 is made to conform in shape to the arcuate flanges 55 of the grate sections 41 and is closely spaced therefrom as shown at 76. A sealing means may also be employed between the walls 76 and the flanges 55, if desired.

The dump grate 12 is of conventional construction and as shown, is hollow for the reception of air and is mounted upon channel irons 80 in the furnace bridge wall, which irons serve as an air duct to supply air through the cooperating ports 81 and 82 to the interior of the dump grate 12, from whence the air is delivered to the refuse upon the dump grate through ports 83. The dump grate is'pivoted to swing near its rear edge upon a shaft 84, as is common with constructions of this character. I

The mode of operation-of a stoker furnaw constructed as above described is briefly as follows: Fuel from the hopper 32 is fed in- 16 by means of the rams 31. The fuel passes over the underfeed grate and is largely consumed thereon. Theresiduum of the fuel is delivered to the overfeed grate in a highly heated condition conducive to agglomeration,

- or the formation of clinker masses. The rel'y fine and loose condition in order that air delivered to this residuum of the fuel upon the overfeed grate may have access to the combustible matter therein. This result is effected with a high degree of efliciency by causing an oscillatory movement of the grate sections 40 and .41. The oscillatory movement is imparted directly to the grate sections 41 by the engine 60, and to the grate sections 40 by means ofthe overlapping relation of the grate sections 40 and 41, the rear ends of the grate sections 40 rising and falling with the forward endsof the grate sections 41. The length of the path of travel of the residuum over the overfeed grate 11 and the thorough agitation of the residuum during its travel thereover insure a com plete burning of the combustible content therefrom. The clinkerand ash, practically free of combustible matter, are periodically discharged to the pit 13 by means of the dump grate 12.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spiritthereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by'the prior art or as are specifically set forth in the appended claims.

What I claim is: i

1. In a stoker,the combination with an underfeed grate, of an inclined over-feed no grate receiving fuel therefrom and comprising two oscillating grate sections, the forward grate section being pivoted at its forward end and the rear grate. section being pivoted at a central'portion, said grate sections being so associated that the oscillation of the rear grate section also efi'ects an oscillation of the forward grate section, and means for oscillating the rear grate section.

2. In a Stoker, the combination with an underfeed grate, of an inclined over-feed grate receiving fuel therefrom and comprising two oscillating grate sections, the forward grate section being pivoted at its forward end and therear grate section being pivoted at a central portion, the forward grate section overlapping the rear grate section in. all positions of oscillations, whereby sifting of fuel therebetween is minimized, said grate sections being so associated that 130 the oscillation of the rear grate section also effects an oscillation of the forward grate section, and means for oscillating the rear grate section.

3. In a stoker, the combination with an 'underfee'd grate, of an inclined overfeed' grate receiving fuel therefrom and comprising two oscillating grate sections, the forward grate section being pivoted at its for- 10 ward end and the rear grate section being pivoted at a central portion, the forward grate section overlapping and being supported by the forward end of the rear grate section in allpositions of oscillation and means for oscillating the rear grate section. a

In testimony whereof, I have hereunto subscribed my. name this 24th day of May, 1923.

OTTO ARAM. 

